1. Field of the Invention
The invention relates to an improved method of quantitatively determining either or both of chloromethyl methyl ether and bis-chloromethyl ether present in a fluid sample, i.e., in a gas such as air or the atmosphere above an organic reaction medium, or in a liquid such as an organic reaction medium or stream, such as the reaction mixture occurring in the manufacture of ion exchange resin. The invention more particularly relates to an improved method of determining chloromethyl methyl ether or bis-chloromethyl ether at a concentration as low as 0.1 part per billion (ppb).
2. The Prior Art
In fairly recent times industrial health and safety work has come to encompass studies of the effects on human subjects of being exposed to even very low levels of chemical substances dispersed in the plant environment in which production workers carry on their duties. Very recently concern was raised about the possible adverse effects of exposure to chloromethyl methyl ether, a reactant used in the manufacture of ion exchange resins, and to bis-chloromethyl ether, a compound formed under certain conditions in the manufacture of chloromethyl methyl ether. Chloromethyl methyl ether (CMME) is at least irritational to the eyes and bis-chloromethyl ether (bis-CME) is apparently a carcinogen. It is of interest to determine the concentration of the bis compound in a product stream as this concentration usually has a direct bearing on the amount which escapes into the atmosphere in the vicinity of a chemical manufacturing process in which the bis compound occurs. It is also of extreme interest and importance to determine the concentration level of both of these compounds in a plant environment so that meaningful toxicology studies may be carried out for that level of exposure. It is of vital importance that such detection methods are available for the protection of industrial workers.
In early studies of the occurrence of chloromethyl methyl ether and bis-chloromethyl ether resort was had to use of a gas chromatograph in combination with a mass spectrometer, but studies showed that the high level of toxicity of these compounds necessitated their detection at concentration levels somewhat below the capabilities of this instrument combination.
In more recent work, the subject of the said copending patent application, it was discovered that greatly improved sensitivity was obtained upon (1) bringing a fluid sample containing either or both of these ethers into admixture with an alkali metal salt of an organic hydroxy compound such as a lower alcohol or an aromatic hydroxy compound such as a phenol, and preferably a chlorophenol, in lower alcohol medium, whereupon an even more complex ether is formed, by way of a derivative, (2) adding water and immiscible organic solvent to the reaction mixture and taking up the derivative into the solvent phase, (3) directing at least a portion of the solvent phase onto a gas chromatograph, and (4) eluting with an inert gas such as nitrogen, whereby such derivative is readily separated on the column with great specificity and sensitivity and is readily detected, as by a flame ionization detector, and more preferably by an electron capture detector when the derivative is of a halogenated organic hydroxy compound with one of the ethers.